A revolutionary breathalyser device which could eventually see patients diagnosing their own illness and prescribing the appropriate medicine is under development in the UK.

Scientists at Imperial College of Science, Technology and Medicine, London, have linked up with joint venture company BodiTech to develop the device whose intvention could be as significant as that of the thermometer.

Trials are expected to begin on a hospital prototype within two years.

Patients taking part are likely to be people who have been prescribed antibiotics for colds and coughs as well as asthma sufferers.

Scientists hope that within five years they will be able to develop a miniature version of the hi-tech breathalyser which can be used by GPs.

Eventually it may be on sale to patients.

Breath odour

The technology market calculates the device could be worth £13bn worldwide.

Many people are unnecessarily prescribed antibiotics for colds

It works by analysing breath odour. It can detect very low levels of chemicals which indicate whether certain bacteria are present in the throat, lungs and nose.

Conditions it could treat include liver and renal failure which both produce distinctive odours, as well as diabetes and asthma.

Asthma causes the lungs to give off vapours which the breathalyser could measure.

Sufferers would be able to tell if they were taking the right level of steroid treatment.

As well as diagnosing which forms of bacteria are present and it will also act as a guide for prescribing medicine and reduce the use of antibiotics.

Scientists claim it can tell the difference between viruses, which do not respond to antibiotics, and bacteria; identify the type of bacteria present; and advise on which antibiotic will treat it most effectively.

Antibiotics

By distinguishing between bacterial and viral infection, it could greatly reduce prescriptions for antibiotics.

There are fears that overuse is leading to the rise of drug-resistant superbugs.

It is estimated that half of all prescriptions for antibiotics are unnecessary.

Professor Peter Openshaw, a member of the Imperial research team, said the technology behind the device had been around for several years.

However, it was only now that scientists had produced a device which was small enough to use in medical diagnosis.

"We think an awful lot of information is contained in the exhaled breath which is not being used at the moment," he said.